mydartswinger

Rafael is stating that you do not have to be out of ground effect to effectively trim a helicopter. The trim of the helicopter is not effected by ground effect because ground effect will not cause the heli to move in one specific direction all of the time. It will, however, cause the helicopter to be a bit more unpredictable. For example, if the helicopter is going to the right, you give it left cyclic to correct, release the left cyclic command, and the heli wants to continually go back to the right, you may need to add left cyclic trim. This will happen even in ground effect.

In saying that, he also stated that the heli is in ground effect until it reaches the altitude of roughly the diameter of the main rotor. You stated to get into a 1 foot hover to get out of ground effect. If your rotor diameter is 28", you'd have to be in a hover of just over 2 feet to get out of ground effect. The heli in question from the OP is a Raptor 50, which has a 4 foot rotor diameter, so for him to be out of ground effect, he would have to be in about a 4 foot hover to get out of ground effect.

To caveat the trim discussion, you can trim the cyclic (right stick) using the radio trims and subtrims. However, when the tail needs trimmed, you must trim it using the ball links on the tail rotor control pushrod coming from the tail servo (mechanical trim). The reason you do not want to trim the tail using the radio is that the gyro is looking for a mechanical center when returning the tail rotor to it's center position. By using radio trims, you will cause the gyro to find only the radio trim, thus confusing the gyro, causing it to overwork and possibly burn out the tail rotor servo. In addition, you will constantly be chasing the tail rotor trim. One flight it will be fine, the next you may have to trim it the opposite direction, and a third flight may have to be trimmed back to the original position. If, for some reason, you cannot get it perfectly centered using the mechanical trim, you can use just a couple of clicks of radio trim AT MOST. If you have to use more than that, re-center the radio trim and use mechanical trim.

Rafael23cc

My Feedback: (6)

I have 10 helicopters. Ranging from a couple of 450s to a couple of 90s. That means that my rotor diameters range from about 30" to about 60".

What is the point of your statement?

To be "outside" of ground effect, you need to be higher than your rotor diameter. Of course, we all know that rotor diameter is influenced by weight. And downthrust is in direct correlation with the weight. So the heavier a helicopter is, the higher you have to fly to be outside of ground effect.

I see that mydartswinger added to my comments. Thanks!

Rafael

Solman

First of all, you only picked out part of the the quote which doesn't make any sense the way you posted it. Second of all, this is what I found on the ground effect which states half the rotor length compared to you saying the full rotor length.

http://www.rchelicopterfun.com/ground-effect.html

I don't admit to being an expert and if I am wrong, feel free to point it out. A similar comment was already posted before you chimed in and you don't have to be rude about it. I do try to do as much research on the matter and I have been in the aviation field for 21 years. Helicopters aren't my specialty, but I am learning fast.






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karlik

Ummm - I'm sorry I asked now. []

Rafael23cc

My Feedback: (6)

Don't be sorry, You asked a question and you got the answer. The fact that it sparked a discussion is actually beneficial for all as you can learn much more than just going away with the answer to a simple question.


By english not being my first language, and you not being able to see my face as I'm typing this, I think you are taking this a little too far, don't you think? What was rude about it? That I asked you what was your point? Is that a rude question? Or are you used to that question being rude in your opinion? I did not mean to offend anybody. We are here to learn.

I've been trying to tell you that ground effect is variable based on rotor diameter, and then you start plugging-in numbers by stating the actual measurement of your helicopter's rotor. My answer is based on my experience of multiple helicopters of multiple sizes.

Your quote answers and settles this discussion. It starts at about a full rotor diameter and gets stronger as you get closer to the ground.

I did not read the article in the link fully, It seems like they recommend that you fly in ground effect. What it seems to me they fail to warn is that cyclic is going to be a little more sesitive in that region. The heli is in fact sitting on top of a high pressure bubble. Imagine yourself trying to stand on top of a beach ball.

Rafael

Solman

When you start off talking about "What's your point" and you then mention about having 10 helicopters, it comes off the wrong way. My apology's if taken in the wrong context. Sometimes replies come across the wrong way. All good.